Komodo IDE : Powerfull enough for editing css, js, html and python. It has good code completion support, and can debug python. Also has a good source browser. Bu it is commercial and somehow it seemed slow for me while editing files, changing editor windows.

So far the ideal editor was the Komodo IDE. But I have new a candidate : NetBeans ! An early access edition of Netbeans with Python support is released. It can be downloaded from here. It nearly have all the features that I want from an editor :